Techniques Of Chromosome Doubling Of Gamete Of Eucommia Ulmoides Oliv.by High Temperature Induction

Eucommia ulmoides was one of peculiar precious medicinal plants growing in China. The gutta-percha was considered as a rubber source to replace caoutchouc. Techniques of pollen chromosome doubling of Eucommia ulmoides has been carried out based on the process of meiosis of microspore mother cell and macrosporogenesis. And the differences of activity between 2n pollen and nomal pollen were analysed. Techniques of megaspore chromosome doubling also were discussed.(1) Conditions of inducing polien chromosome doubling by the high temperature were known. According to the characteristic that the diameter of 2n pollen is generally much larger than that of normal pollen, the ratios of 2n pollen which collected from male buds treated by different high temperatures at different stages and duration were determined. The results showed that the optimal stage of inducing pollen chromosome doubling by high temperature was metaphase I. the optimal treatment temperature was 46℃and the optimal duration was 4h. Due to the meiotic process of microspore mother cells was asynchronous, the optimal stage for inducing pollen chromosome doubling was. to some degree, found to be a relatively wide extention. Therefore,60% of 2n pollen could be obtained treated by high temperature during metaphase I.(2) A lower germination rate for induced 2n pollen by high temperature was demonstrated and germinated slowly. Germination rate, length of pollen tube and moving speed of sperm nucleus of n pollen and 2n pollen derived from the treatment by high temperature were observed. The results indicated that he germination rates for these 2n pollen or n pollen were much lower than that of n pollen derived from the control treatment. The length of pollen tube of 2n pollen was shorter than that of n pollen in the same unit time. What’s more, the moving speed of sperm nucleus of 2n pollen was much slower than that of n pollen.(3) One triploid Eucommia ulmoides were obtained through inducing megaspore chromosome doubling by high temperature. Based on the grasp of the process of megasporogenesis and the development of embryo sac, it was in the first day after male buds maturated that one triploid was obtained from the event that applying 48℃treated female buds for 4 hours This suggested that inducing triploid by high temperature during megasporogenesis was possible. An observation of the stoma size and density between triploid and diploid was done. The results indicated that not only the content of DNA and chromosome numbers had great differences, but also the stoma size and density had significant differences between triploid and diploid. Triploid had larger stoma size, and lower stoma density.